In modern radio network system construction, in-building coverage has become the most important part in network construction. An appropriate in-building coverage scheme can give full play to the network, create more profit and save the cost of the network construction for an operator as well, realizing low investments but high returns. Thus a radio access device called a Home NodeB (HNB) emerges because of demands. The HNB is deployed in private occasions such as a home, a team, a company or a school as dedicated resources for a private subscriber. It is able to provide the subscriber with various kinds of high speed radio access services with favorable fees, and meanwhile it overcomes the inadequate coverage of an existing distributed cellular wireless communication system.
Currently, the HNB mainly has three access modes: an opened mode, a closed mode and a mixed mode. An HNB in the opened mode allows access of all subscribers, and this HNB cell thereof is a macro cell. An HNB in the closed mode only allows access of an authorized subscriber, such as a family member, a team member, etc. These authorized subscribers are called a non-public authorized subscriber group or a Closed Subscriber Group (CSG), and authorizing information is stored in a Universal Subscriber Identity Module (USIM) of a User Equipment (UE). An HNB in the mixed mode allows access of all subscribers, but a subscriber belonging to the CSG has priorities or privileges. A cell under the coverage of a macro NodeB or eNodeB is called a macro cell, and a cell under the coverage of an HNB is called a CSG cell with a CSG Identity (ID). Through determining the access mode of an HNB which a CSG cell belongs to and/or allowed CSG list (or CSG whitelist) information stored in a USIM card, a UE can determine whether a CSG cell allows it to access. For a specific UE, the number of the CSG cell allowed to access is limited. Thus the UE can store the CSG cell information which has accessed before, which is called footprint/fingerprint information. Based on the footprint/fingerprint information, the UE is able to access to the CSG cell accurately and rapidly during a reselection and a handover.
The HNB can use frequency resources reserved for the HNB by the operator, which is called a CSG dedicated frequency; it can also use identical frequency resources of the macro NodeB, which is called a mixed frequency. The cells with identical frequency are identified by a Physical Layer Identity (PCI), and when the HNB and the macro NodeB use identical frequencies, the operator reserves dedicated PCI recourses (i.e. PCI split) for the HNB, and the CSG cell uses the PCI in the PCI split. The same as the macro cell, the CSG cell has a PCI and a Cell Global Identifier (COI). Due to the limitation of the PCI, the PCI cannot solely represent one CSG cell with the wide deployment of the HNBs. However, the CGI is exclusive within a Public Land Mobile Network (PLMN), therefore the UE and the macro NodeB can only identify one CSG cell by obtaining the CGI.
With the wide deployment of the HNBs, the UE is certainly required to be handed over between the macro cell and the CSG cell or between the CSG cells in order to meet demands on mobility. Because the HNB is a plug-and-play device with mobility and is widely deployed, generally neighboring cell relation between the macro cell and the CSG cell will not be set, i.e., the UE cannot obtain information of a neighboring CSG cell when it is handed over from a macro cell to a CSG cell, and the UE needs to real-time detect and obtain information such as a CSG ID, a CGI, a Tracking Area Code (TAC) and a PLMN and the like for a handover. At the same time, because the UE has priorities or privileges in some authorized CSG cells, access control needs to be performed for the UE during a handover so that only the authorized subscriber can access the HNB cell in the closed mode. The failure of the handover access control may be caused by delayed update of the allowed CGS list reserved by the UE, or by a malicious UE which intends to access the CSG cell in the closed mode to get priorities or privileges. The current protocol does not involve this issue. If a proper processing method is not adopted, the UE may still assume that the CSG cell is accessible, and continue sending a measurement report. A network side may send a handover request to a target CSG cell again after receiving the measurement report, which results in signaling consumption between interfaces and affecting performance of the network.